David (L) and Simon Reuben, who topped The Sunday Times Rich List 2016

Property investors were among the strongest performers in The Sunday Times Rich List 2016, as their wealth outperformed the index. Sibling property tycoons David and Simon Reuben topped the list of Britain's wealthiest people after seeing their net worth rise by £3.4bn ($4.9bn) to £13.1bn. Included in their property portfolio is the Millbank Tower in the heart of Westminster, home to Conservative Party HQ.

Of those on the 1,000-strong rich list who have significant investments in property, 100 saw their wealth increase over the past year; seven were new entries; 39 saw no growth or loss of wealth; and just 19 saw their wealth drop. The combined wealth of those with investments in property in 2016 is £137.8bn, though many have other assets.

Proportionately, property investors outperformed the whole rich list. Of those with property portfolios, 60.6% saw their wealth increase against 49.6% of the rich list. Moreover, just 11.5% of property investors saw their wealth fall during the year, compared to 16.8% of the rich list.

"A lot of the people with property interests, as part of their portfolio interests, have those investments in commercial rather than residential property," said Trevor Abrahmsohn, managing director of Glentree Estates, a luxury property agency in London, to IBTimes UK.

"They obviously own lovely homes, I'm sure, in London. And I'm sure those lovely homes have had a correction in value in line with other quality residential properties in London. But that will be a relatively small part of their overall wealth. Their wealth will come from their portfolios that either they own directly, or own in funds, etc.

"In the main, commercial property has done well over the last few years... Commercial property lagged behind residential property for a number of years, particularly after 2008, when there was a contraction... and then, over the past three, four years, it has done remarkably well."

Near the top of the rich list is the Duke of Westminster, owner of Grosvenor Group, whose wealth increased by £790m to £9.35bn, taking him up to sixth place. Grosvenor is invested heavily in London property, owning swathes of commercial and residential space in the city's most expensive postcodes.

Britain's Duke of Westminster, Gerald Cavendish GrosvenorReuters

Next on the property rich list is the Barclay brothers, owners of Telegraph Media Group, who climbed to twelfth place with a £500m increase in their wealth, making them worth £7bn overall. "The Barclay twins last year sold their stake in the Maybourne Group of luxury hotels, comprising Claridge's, the Berkeley and the Connaught in central London," said The Sunday Times. The deal was worth £2.4bn. They still own the Ritz Hotel.

Earl Cadogan and his family, who rose to sixteenth place, are worth £5.7bn after a £900m rise. They are heavily invested in London property, both residential and commercial in large swathes of Chelsea, through the Cadogan Group company.

Following Cadogan in the property rich list is a new entry, the American financier John Grayken, who at twentieth place is worth £4.4bn. "The British property operation Quintain was bought for £700m in July by the US private equity firm Lone Star," according to The Sunday Times. "Quintain has planning permission for around 5,500 homes in the Wembley area. Lone Star is headed by ex-Morgan Stanley banker Grayken, 59, who was born in Boston and lives in a Surrey mansion. He founded Lone Star in 1995."

However, investors in British property face a torrent of tax rises, including an annual levy on homes owned by offshore entities, an extra 3% levy on top of basic stamp duty rates for purchases of additional properties, and higher stamp duty for more expensive commercial buildings.

Glentree's Abrahamsohn said Osborne's tax increases on high-end property, and his abolition of non-dom tax status, are hurting the market. He said 70% of his wealthy non-dom clients now plan to sell-up and pull out of London, "which is a great pity" because most pay tax in the UK.

"How can we afford to expel — because that's what we're doing — these wealth creators? How can any nation afford to lose these wealth creators? They can't. This is one of the reasons why the chancellor is losing credibility for his financial governance."

Moreover, a weaker global economy caused by falling commodity prices and China's slowdown, is denting demand for luxury property, making it a less attractive investment as potential future returns dwindle. Prime London property prices saw their slowest annual growth rate for six years during March 2016. On average, prime property prices in the city grew by just 0.8% over the year, according to the estate agent Knight Frank in its London Residential Review.

The finance boss of Grosvenor Group, whose owner the Duke of Westminster is sixth on The Sunday Times Rich List, warned of an imminent correction in the property market, after years of sharp price increases in booming London. "The balance of probability has increased quite dramatically that there is going to be a correction of some kind," Nicholas Scarles, finance director at Grosvenor Group, told The Times, adding "it is only a matter of time". He also said Grosvenor was preparing for the eventuality by offloading some of its property assets.

Property investors were in the spotlight amid the Panama Papers leaks. Documents from offshore services firm Mossack Fonseca, which leaked to the International Consortium of Investigative Journalists (ICIJ), showed the world's political and financial elite using tax havens to purchase property in London. The biggest of those investors was the president of the United Arab Emirates (UAE), who holds swathes of residential and commercial property in Mayfair, thought to be worth billions.